A certain number of headlights are already known that are fitted with a ventilation channel between the space inside the headlight and the outside. Conventionally, such a ventilation channel must be designed to ensure that air can flow in both direction between said inside space and the outside so as to cope with pressure increases and decreases caused by changes in the temperature of the headlight on being switched on and off in succession, while simultaneously ensuring that no moisture condenses on the cold walls of the headlight. At the same time, such a channel must also keep the inside space of the headlight, and more particularly its lamp, at a temperature that is reasonable, particularly for the purpose of ensuring that the lamp retains a normal lifetime.
Simultaneously, such a ventilation channel must be designed to avoid any water, mud, etc. . . . penetrating into the inside space of the headlight, particularly when the vehicle is travelling in the rain or while the engine compartment is being cleaned by means of a high pressure jet, or the like.
A known solution to this problem consists in defining at least one annular channel that opens to the outside in a bottom region and that opens to the inside space of the headlight in a top region. This may be done, for example, by means of appropriate dispositions obtained by molding on the rear face of the reflector and by an appropriate shape for a closure cover or cup pressed against said rear face.
Document FR-A-2 600 145 in the name of the Applicant describes a headlight of that type.
However, presently known ventilation devices having a single cooling and ventilation channel suffer from the major drawback of not cooling the lamp sufficiently. The lamp therefore operates at a high temperature and its lifetime is thus reduced.